1. Field of the Invention
The invention relates to slide fasteners and particularly to spiral slide fasteners employing interlocking coils of filamentary material woven to supporting tapes.
2. Description of Prior Art
The prior art, exemplified by U.S. Pat. Nos. 2,296,880, 2,651,330, 3,123,103, 3,143,779, 3,454,052 and 3,791,417, British Patent No. 548,819, and Canadian Patent No. 538,883, contains several spiral slide fasteners employing interlocking coils of filamentary material woven to supporting tapes. Many of the prior art fasteners employ a supporting bead formed from a plurality of longitudinally extending warp threads and one or more longitudinal cords or yarns bunched in a bundle or package with interwoven weft threads holding the coil against the bead providing support for the coil; however, the package of threads and cord or yarn results in a slide fastener which is more rigid and more expensive to manufacture, and sliders on the fasteners engage the bead or textile package resulting in more difficult operation of the slider as well as wear and failure on the threads. Prior art spiral fasteners which do not employ a bead or textile package have been subject to failure in that the coils are not satisfactorily supported by the tapes and distortion and displacement of the coil occur resulting in failure of the fastener.
U.S. Pat. Nos. 1,947,508, 2,651,092, and 2,940,478 disclose slide fasteners having tapes with rows of fastening elements secured on respective beaded edges of the tapes wherein the tapes have a reduced thickness adjacent the fastening elements.
U.S. Pat. No. 3,765,457 discloses a row of dome members in the form of a spatial meander attached to the edge of a carrying band by a weft thread woven in a plurality of warp threads.
SUMMARY OF THE INVENTION
The present invention is summarized in that a stringer for a spiral slide fastener includes a coil of filamentary material forming successive convolutions with locking portions joined by supporting portions, a woven tape having first and second pluralities of longitudinally extending warp threads and a plurality of transversely extending weft thread segments interwoven with the first and second pluralities of warp threads, the first plurality of warp threads having thicknesses less than a predetermined thickness and extending side by side in the tape from the coil, a plurality of weft thread loops interconnecting respective pairs of weft thread segments and extending around respective supporting portions to hold the supporting portions of the coil to the edge of the tape, and the second plurality of warp threads having thicknesses greater than the predetermined thickness and being spaced from the coil by the first plurality of warp threads. pg,4
An object of the invention is the elimination of the bead or package supporting the coil to produce a less expensive and more flexible fastener.
Another object of the invention is to support the coil in a manner to withstand lateral stresses without failure.
It is also an object of the invention to utilize a smaller slider.
A further object of the invention is to provide a slide fastener with reduced wear and tear on the threads.
It is a still further object of the invention to make a smaller fastener suitable for light duty use.
Other objects and features of the invention will become apparent from the following description of the preferred embodiment when taken in conjunction with the accompanying drawings.